The F-Secure Client Security products started sending security alerts to F-Secure Policy Manager for every single blocked URL. This started when F-Secure Online Safety 2019-09-02_02 update was released.
The security alerts have following details:
Unknown alert: online_safety.page.block.
The fix was released in the F-Secure Online Safety 2019-09-10_01 update package. The update is installed automatically and does not require user or administrator actions.